Ultraviolet observations are a primary tool for probing the hot atmospheres of cool, planet-hosting stars (spectral types F – M). The 10 – 320 nm ultraviolet bandpass contains key diagnostics of the full temperature range from the chromosphere to the corona, is the most sensitive bandpass for stellar flares studies, and can provide direct constraints on stellar coronal mass ejections. After their emission from the star, high-energy photons and particles regulate the atmospheric temperature structure and photochemistry on orbiting planets, influencing the long-term stability of planetary atmospheres and driving atmospheric photochemistry. As the field of exoplanet characterization has grown over the past decade, so have large ultraviolet survey programs targeting cool stars. In this talk, I will give an overview of recent key results from ultraviolet studies of cool stars (focusing on the “extreme ultraviolet” bandpass, 10 – 91 nm), with an emphasis on implications for atmospheric escape. I will conclude by presenting the landscape for stellar and exoplanetary investigations utilizing ultraviolet observations over the next two decades. Missions of all sizes have important roles to play in this area: I will highlight planned or proposed missions ranging from cubesats and smallsats (CUTE, SPARCS, SPRITE, and MANTIS) to Explorer class missions (ESCAPE) to flagships (the “Large IR/O/UV Surveyor”).